Skip to content

A whole power of the radicand under Euler's substitution is read as one - #1774

Merged
Rafael-SOWNet merged 1 commit into
masterfrom
a-whole-power-of-the-radicand-is-not-read-as-one-of-its-root
Oct 5, 2026
Merged

Rafael-SOWNet merged 1 commit into
masterfrom
a-whole-power-of-the-radicand-is-not-read-as-one-of-its-root

Conversation

@Rafael-SOWNet

Copy link
Copy Markdown
Member

Closes #1770.

Euler's substitution read a whole power of the radicand, Q^n, as the root to the nth power, which is Q^(n/2), and integrated another integrand than the one asked:

integrand 2.5.0 master 85d6601c this
1/((x^2 + 3)^2 (x + sqrt(x^2 + 3))) declined wrong at every real point -2/((sqrt(x^2 + 3) + x)^2 + 3)^2
1/((x^2 + 2x + 3)^2 (x + sqrt(x^2 + 2x + 3))) declined wrong at every real point a rational function of x + sqrt(x^2 + 2x + 3)
(x^2 + 3)^2/(x + sqrt(x^2 + 3)) declined wrong: over [0.2, 1.7] it changes by 2.08, where the integral is 8.48 declined

What changes. The substitution writes the radicand's powers in its variable as powers of the root, Q^(k/2) as the root to the kth; a whole power Q^n is the root to the 2nth now. Read so, Q^2/(x + sqrt(Q)) is a rational function past the substitution's bound on the degree, and is declined, as 2.5.0 declined it.

Tests: WholePowerOfTheRadicandUnderEulerTest, the first two rows differentiated back at five points, and the third answered rightly or not at all.

The full suite on the head, efa13a6b, passes, 14,928 tests, and the library builds for netstandard2.0. The head is one commit on master 85d6601c.

🤖 Generated with Claude Code

https://claude.ai/code/session_012sonx8iAspMiwRwokT1Ura

Euler's substitution writes the radicand's powers in its variable as powers of
the root, and read a whole power Q^n as the root to the nth, which is Q^(n/2), so
it integrated another integrand than the one asked: Q^2/(x + sqrt(Q)) was answered
as Q/(x + sqrt(Q)). It reads it as the root to the 2nth now.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012sonx8iAspMiwRwokT1Ura
@Rafael-SOWNet Rafael-SOWNet added this to the 2.6.0 milestone Oct 5, 2026
@Rafael-SOWNet
Rafael-SOWNet merged commit 4105b3b into master Oct 5, 2026
34 checks passed
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Labels

None yet

Projects

None yet

Development

Successfully merging this pull request may close these issues.

Euler's substitution reads a whole power of the radicand as half of it

1 participant